The present invention relates to a powdered-paint spraying plant with variable-section booth.
Currently, the greatest problem involved in using powders in industrial painting lies in the need to completely clean all the equipment used every time a color change is required. This cleaning operation requires the stoppage of the plant for the time necessary to perform accurate cleaning.
The direct consequences of this are long downtimes, with a considerable decrease in plant productivity, an increase in running costs and a lower quality of the painted surfaces caused by damage-producing loitering of the pieces along the overhead chain conveyor inside the pretreatment tunnels and in the polymerization ovens.
In order to at least partially obviate the downtimes caused by color changing, it has already been proposed to resort to some contrivances: for example, pre-scheduling is performed with the aim of grouping into batches all pieces having the same color.
However, this type of scheduling entails the need to mix different orders in favor of color groupings.
It has also been suggested to purchase multiple painting booths with the associated accessory equipment (reciprocators, dispensers, feeders etc.) in order to use each painting plant for just one specific color.
Although this solution is satisfactory from the technical point of view of painting quality, it entails an enormous investment, requires the availability of a very large space to be devoted to the plants and in any case can be used for a rather limited number of colors (no more than two or three).
Furthermore, if the various components of each painting plant are arranged in parallel, the overhead conveyors must be of the two-rail type. Such conveyors cost up to three times as much as conventional single-rail conveyors.
Furthermore, third-party painting firms, in order to satisfy their various clients, must be able to provide a very wide range of colors. They are therefore forced to paint small batches with waste, i.e. without being able to recover the overspray paint, to avoid the drawbacks of plant halting due to color changing. All these problems have not been solved yet, also because spraying devices and booths are currently manufactured by a small number of specialized manufacturers.
In practice, therefore, it is extremely difficult to achieve the optimum conditions required to reduce downtimes.